When a car has a collision, the driver may collide with the steering wheel secondarily due to inertia. Thus, in order to protect drivers, a shock absorbing steering column apparatus has been widely employed.
In a shock absorbing steering column apparatus, when a driver has a secondary collision and the shock energy of this collision works from the rear part to the front part of the car, the steering column is disconnected from the car body to move to the front part of the car while being collapsed, and absorbs the shock energy meanwhile.
Generally, the steering column is supported and secured to the car body at two positions, that is, at an upper bracket on the rear part of the car and a lower bracket at the front part of the car.
The upper bracket of the steering column in the rear part of the car is provided with the shock absorbing mechanism described above, in addition to a tilt lock mechanism, and the like.
On the other hand, the lower bracket in the front part of the car is provided with a supporting pin serving as the center of tilting so as to move the steering column in an inclined manner at the time of a tilt operation. At the same time, such a structure is employed as smoothly disconnecting the steering column from the lower bracket when the steering column is collapsed to move to the front part of the car at the secondary collision described above, so that the steering column can be securely guided to the front part of the car without falling downward.
For example, in Japanese Patent Application Laid-Open No. 2002-59853, a column-side lower bracket which is secured to a steering column is formed with an axially elongated hole and a partition member which is cut up from the inner periphery of this axially elongated hole.
The column-side lower bracket is brought into contact with a body-side lower bracket which is secured to the car body, and a supporting pin is passed through these both lower brackets. In this case, the supporting pin is passed through the partition member on the front side of the car inside the axially elongated hole of the column-side lower bracket.
When the tilt operation is performed, the column-side lower bracket can be inclined together with the steering column around the supporting pin serving as the center of the tilting.
At the secondary collision, when the steering column is collapsed to move to the front part of the car, the body-side lower bracket and the supporting pin remain stationary. On the other hand, the column-side lower bracket moves to the front part of the car together with the steering column. As a result, the partition member is broken by the supporting pin, whereby the steering column can be smoothly disconnected from the lower bracket.
After that, the column-side lower bracket is, while the axially elongated hole thereof is engaged with the supporting pin, moved to the front part of the car together with the steering column. Thus, since the structure is that the support pin is engaged with the axially elongated hole, it is possible to guide the steering column to the front part of car without fail without dropping the steering column downward.
However, in the structure disclosed in Japanese Patent Application Laid-Open No. 2002-59853 described above, the partition member which is broken in the secondary collision, has been cut up from the inner periphery of the axially elongated hole of the column-side lower bracket and is formed with the column-side lower bracket as a unitary structure, so that an elaborate processing thereon is not feasible.
When the partition member is broken and is deformed, the base of the partition member is swollen out, so that there is a fear that the steering column is not always smoothly disconnected since it may be caught when collapsed.